Composition for use in a laundry washing machine

ABSTRACT

The invention relates to a composition for use in a washing machine. The composition is characterised by a base composition that becomes active essentially during the main wash cycle of the washing machine; and by at least one particle with at least one core which contains at least one substance which becomes active essentially during the rinse cycles of the washing machine and with a coating which essentially fully encloses the core(s) and contains at least one compound whose solubility increases as the concentration of a specific compound in the surrounding medium decreases. The invention provides for means that prevent a significant dissolution of the coating or a significant detachment of the coating from the core(s) until the rinse cycles have begun. The invention also relates to a method for carrying out a wash cycle in a washing machine using the inventive composition.

The present invention relates to a composition for use in a washingmachine and to a process for the use thereof.

Although modern washing machines usually have numerous different washingprograms, which differ with respect to the duration and temperature ofthe individual washing and rinsing cycles, a washing programsessentially comprise the following basic steps: prewashing cycle, mainwashing cycle, several rinsing cycles and spinning cycle. Whilst theactual detergent which is intended to give rise to the cleaning actionis added at the start of the main washing cycle (or optionally at thestart of the prewashing cycle), during the rinsing cycles special agentswith different functions can be used. These special agents for therinsing cycles are intended to mainly bring about further advantages forthe washing treatment. A non-exhaustive list of such agents and withoutrestriction thereto comprises fragrances (pleasant smell of thewashing), fabric softeners (softness of the washing), antistatic agentsreduction or prevention of the build-up of static electricity in thewashing), agents for restoring the capacity of the washing to absorbmoisture, mild acids (beaking down incrustations or neutralization ofalkalinity), bleaches, either having an oxygen or a chlorine base(improving the cleaning action), disinfectants, agents for a persistentprotection of both the washing and the person wearing the latter againstinsects or cites, agents for an improved removal of grease marks,finishing agents giving a protection against creasing, opticalbrighteners, ironing auxiliaries (to facilitate ironing of the washing),agents for inhibiting dye transfer, enzymes such as cellulases, lipases,etc. for special uses.

The described different functionalities have hitherto been achieved (ifat all) by charging different products, partly via separate dosing orcharging devices, as well as charging at different times.

The aim of the present invention was to combine within a single productthe cleaning function and the function or functions of the substance orsubstances to be added during the rinsing cycles, with a constantefficiency compared with the results achievable with a separate dosingor charging, or to permit the charging of further substances in therinsing cycles. DE-OS 20 65 153 and DE-OS 20 07 413 disclose detergentpellets for use as washing agents, in which it is inter alia provided tocombine two components with different functionalities. The structure isformed from a covering or enveloping shell, which is e.g. formed fromtwo shell halves, which comprise a cleaning agent, and a cavitysurrounded by the shells and which contains additives such as softeners,brighteners, etc.

British patent 1 390 503 discloses a liquid cleaning agent or detergentwhich contains capsules, which are insoluble in the composition, butrelease their content when the composition is diluted with water. Thisobjective is achieved in that the capsules are coated with a substance,which has a poor solubility in water solutions with a high ionicstrength, but which is soluble if the ionic strength is reduced bydilution. It is pointed out that this procedure can be used in order toincorporate materials into the liquid cleaning agent, which in thelatter are unstable or would produce an instability if added directly.It is also proposed to use this procedure for delaying the release of aspecific substance. Reference is made to use in detergents. Theencapsulated material is released within two minutes following thedilution of the cleaning agent with water, i.e. during the main washingcycle.

U.S. Pat. No. 4,082,678 describes a fabric conditioner, which comprisesa closed container containing a releasable agent and which is used formaking water-insoluble or non-dispersible an inner container located inthe first container and which is normally water-soluble orwater-dispersible, the inner container containing a fabric conditioner.The inner container comprises a substance, whose solubility in water ishighly dependent on the ionic strength or the pH-value of the medium andthe agent used for rendering the inner container insoluble is an agentfor controlling the pH-value or the ionic strength.

Japanese patent applications KOKAI 60-141705, 61-28440, 61-28441,61-28596, 61-28597 and 61-28598 describe processes for the production ofpH-sensitive microcapsules for use in detergents. The pH-sensitivecoating is a copolymer of the following monomers:

A) at least one basic monomer of formula I:

 in which R is hydrogen or a methyl group and R¹ and R² in each case analkyl group with 1 to 3 carbon atoms and x is an integer from 1 to 4,

B) at least one monomer which is insoluble or difficultly soluble inwater and

C) at least one water-soluble monomer.

It is pointed out that the described polymers are insoluble at apH-value of 9.5 or higher and are soluble at a pH-value of 8.5 or lower.Different ingredients of cleaning agent compositions are described,which can be successfully and usefully coated with, the describedpolymers. The aim of the invention described therein is to protectsubstances, which only evolve their function during the rinsing processup to the start of the latter and then to release them as immediately aspossible. A disadvantage of the solution described in these Japanesepatent applications is that the enveloped particles are in directcontact with non-alkaline washing water at the start of the washingcycle, which can give rise to a partial dissolving of the protectivecovering.

Japanese patent KOKAI 50-77406 discloses a washing aid, which issurrounded by a water-soluble covering or envelope, obtained by mixingpolyvinyl acetal dialkyl aminoacetate and at least one organic acid,which is solid at room temperature. This protective envelope is intendedto protect the washing aid during the main washing cycle one to releaseit during rinsing cycles. The described compound reacts to the pH-valuechange between the main washing cycle and the rinsing cycle. Here againthe disadvantage exists of a possible partial dissolving of theprotective envelope at the start of the washing cycle.

European patent applications EP 284 191 A2 and EP 284 334 A2 disclose awater-soluble polymer film for releasing washing additives during therinsing cycle of washing machines, remaining intact during the normalwashing cycle over a range of typical temperatures and rapidlydissolving during the rinsing cycle. These applications point out thatthe use of pH-sensitive coatings was admittedly known, but that thesefilms are normally also temperature-sensitive, so that they do notremain reliably stable during the different temperatures of the washingcycle. The solution proposed is a pH-dependent material (whichundesirably also has a positive, temperature-dependent dissolvingbehaviour) which is combined with a material having a negative,temperature-dependent dissolving behaviour. This combination is supposedto guarantee that the coatings do not dissolve at the high temperaturesat the start of the washing cycle (in particular the very hightemperatures occurring in American machines).

European patent application EP 481 547 A1 discloses multilayerdishwashing machine tablets having a core, a separating layersurrounding the core and an outer layer for the sequential release ofthe ingredients of the different layers. This tablet is fundamentallyintended to solve two problems, namely

1) incompatible materials can be formulated together in a single tabletand released at different times in order to avoid mutual influencing and

2) compositions, which are intended to evolve their functions atdifferent times, can be formulated in a single tablet.

An essential disadvantage of this prior art is that for initiatingdissolving of the covering layer the temperature is used as theinitiating factor, i.e. temperature-sensitive materials are used for thecovering material. As the temperature/time pattern in washing machinescan differ very considerably as a function of the selected program itwould be difficult, if not impossible, to select a material for thecovering which is usable for all possible programs of modern washingmachines. EP 481 547 A1 admits (p 7, lines 37 to 43) that the choice ofthe material of the covering layer must take account of equipment andprogram-specific features. Thus, there is a clear limitation to hepractical usability of the products described. The citation makes tomention of a use for washing machines.

PCT application WO 95/29982 discloses a dishwashing agent with a delayedrelease of a clear rinsing agent in the form of a nonionic surfactant,which together with an inorganic builder salt forms a core particle,which is provided with a wax-like covering in order to ensure thedelayed release. This covering is a substance which does not melt at theoperating temperatures encountered during the cleaning cycle, but whichat alkaline pH-values is so gradually chemically disintegrated thatthere is still an effective clear rinsing agent quantity present at theend of the main cleaning cycle and is transferred into the rinse clearcycle. The citation makes no mention of a use for washing machines.

A disadvantage of the solution described in this citation is that thecovering is rendered soluble by chemical saponification at alkalinepH-values, so that the time at which the clear rinsing substance isreleased from the core is a function both of the temperature and thelength of the main cleaning cycle. The patent application provides noteaching as to how a product is to be formulated with which the clearrinsing agent can be released in the rinsing cycle in all washingprograms of any random equipment type. Finally the product is a mixtureof granular cleaning agents and granular clear rinsing particles.

In view of the prior art, the problem of the present invention is toprovide a composition according to the preamble, which is usable formost washing programs of different washing machine types and in each ofthe said cases only releases the substance or substances intended toexert their action substantially firstly in the rinsing cycles only insaid cycles. The aim is to achieve this without any significantrestriction regarding the choice of detergents used, the substance orsubstances used for the rinsing cycles and other constituents of thecomposition.

According to the invention this problem is solved with a compositionaccording to the preamble, which is characterized by a basic compositionevolving its function essentially in the main washing cycle of thewashing machine, and at least one particle with at least one coreincorporating at least one substance, which evolves its functionessentially in the rinsing cycles of the washing machine, and a coveringsubstantially completely surrounding the core or cores, which comprisesat least one compound, whose solubility increases with decreasingconcentration of a specific compound in the surrounding medium, agentsbeing provided so as to prevent up to the start of the rinsing cyclesany significant dissolving of the covering or significant detachment ofthe covering from the core or cores.

In an advantageous embodiment the concentration of the specific compoundin the local environment of the particle or particles is sufficientlyhigh up to the start of the rinsing cycles to prevent up to this time asignificant dissolving of the covering and a significant detachment ofthe covering from the core or cores.

Preferably the particles are coated with a substance which,substantially independently of the concentration of the specificcompound in the surrounding medium, is dissolved or separated during therinsing cycles of the washing machine.

Preferably the basic composition is in the form of a tablet.

An embodiment of the invention proposes that at least one particle is soplaced in or on the tablet that the concentration of the specificcompound in the local environment of the particle or particles issufficiently high up to a substantially complete dissolving of thetablet in order to prevent a significant dissolving of the covering or asignificant detachment of the covering from the core or cores.

Preferably the or all the particles are received in at least one cavityof the tablet completely surrounded by the basic composition.

At least one cavity contains one or more particles, which alone ortogether substantially have the same volume as the cavity.

Preferably at least one cavity has a larger volume than the or all theparticles received in the particular cavity.

In an alternative of the invention the particle or particles are looselylocated in the interior of the cavity.

In another alternative the particle or particles are fixed in theinterior of the cavity, preferably by an adhesive.

In a further embodiment the cavity is substantially centrally placed inthe interior of the tablet.

The invention also proposes that -he tablet has a single, substantiallyspherical cavity.

According to the invention it is preferable to receive in the cavity asingle, substantially spherical particle, whose external diameter issmaller than the internal diameter of the cavity.

In a further embodiment the or all the particles are received in atleast one tablet cavity, which is only partly surrounded by the basiccomposition.

Preferably the cavity is a depression in one of the tablet surfaces inwhich the particle or particles are at least partly received.

In a preferred embodiment the particle or particles are so received inthe cavity or depression that they do not project over the surface orsurfaces of the tablet.

In a special embodiment, the invention proposes that the cavity ordepression only contains a single tablet, whose volume and shape in thevicinity of the cavity or depression substantially coincides with thevolume and shape of the cavity or depression and substantiallycompletely fills the same.

Preferably the cavity or depression has a substantially circularcross-section face parallel to one of the surfaces to which it opens orin which it is placed.

The invention also proposes that the cavity or depression only opens tosuch an extent towards the surface or surfaces that the particle orparticles received therein cannot pass through the opening or openingsof the cavity or depression.

Preferably the particle or particles are loosely arranged in the cavityor depression.

In another alternative the particle or particles are fixed in the cavityor depression, fixing preferably taking place with an adhesive.

In an embodiment of the invention, the basic composition comprises atleast one composition selected from the group comprising a detergentcomposition, a water softener composition and a washing intensifiercomposition.

In a preferred embodiment of the invention, the covering comprises atleast one compound, which at the concentration of the specific ion atthe end of the main washing cycle of the washing machine is not or isonly slightly soluble and at the concentration of the specific ion inthe rinsing cycles has such a sufficient solubility that it is sosubstantially dissolved in the rinsing cycles or detached from the coreor cores that an at least partial escape of the core material into themedium of the rinsing cycles is permitted.

Preferably the solubility of the compound increases with decreasing OH⁻ionic concentration and therefore decreasing pH-value in the surroundingmedium.

In particularly preferred manner the compound has at a pH-value above 10no or only a limited solubility and at a pH-value below 9 such anadequate solubility that it is so substantially dissolved in the rinsingcycles or is so detached from the core or cores that an at least partialescape of the core material into the medium of the rinsing cycles ispermitted.

Preferably this compound comprises a polymer, in particularly preferredmanner a pH-sensitive polymer, which comprises at least one repeat unit,which has at least one basic function, which is not part of the backbonechain of the polymer.

In a preferred embodiment the polymer comprises at least one repeatunit, which is based on a compound selected from the group comprisingvinyl alcohol derivatives, acrylates or alkyl acrylates having saidbasic function.

According to the invention the polymer is a carbohydrate functionalizedwith said basic function.

The aforementioned basic function is preferably an amine, inparticularly preferred manner a secondary or tertiary amine.

According to a preferred alternative the repeat unit is based on acompound having the following formula III:

in which G is a linking group selected from —COO—, —OCO—, —CONH—,—NHCO—, —NHCONH—, —NHCOO—, —OCONH—or —OCOO—, R₁ independently of oneanother being hydrogen or an alkyl group with 1 to 3 carbon atoms, R₂independently of one another hydrogen or an alkyl group with 1 to 5carbon atoms and x is an integer from 1 to 6.

Preferably the repeat unit is based on a compound with the followingformula IV:

in which R₁ independently of one another is hydrogen or am alkyl groupwith 1 to 3 carbon atoms, R₂ independently of one another hydrogen or analkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.

According to another embodiment of the invention the basic function isan imine or a basic, aromatic N-containing group, preferably a pyridinegroup or an imidazole group.

According to a further embodiment the pH-sensitive polymer is a polymerderived from chitosan.

The invention finally proposes that the compound comprisesK-carrageenan.

According to an embodiment of the invention the core or cores compriseat least one material selected from the group consisting of fragrances,fabric softeners, antistatic agents, agents for restoring the capacityof washing to absorb moisture, mild acids, bleaches, disinfectants,agents for persistent protection of both the washing and the personwearing it against insects or mites, agents for the improved removal ofgrease marks, agents for finishing with protection against creasing,optical brighteners, ironing auxiliaries, agents for inhibiting dyetransfers and enzymes.

In an alternative the core or at least part of the cores can be in theform of an encapsulated liquid. In another embodiment the core or atleast part of the cores is in solid form.

The invention also relates to a process for performing a washing cyclein a washing machine, in which the composition according to theinvention is added at a suitable time during the prewashing cycle ormain washing cycle to the medium located in the washing machine.

In a special embodiment of this process for the case that the basiccomposition in the form of a tablet is unable, following its dissolvingin the medium to make available therein a concentration of the specificion, up to the end of the main washing cycle, which is sufficiently highin order to prevent a substantial dissolving of the covering and asubstantial detachment of the covering from the core or cores, saidadequate concentration of the specific ion is brought about by headdition of a further composition, such as e.g. a detergent composition,to the medium of the main washing cycle at an appropriate time.

The composition according to the invention is characterized in that itdelivers excellent results both in the main washing cycle and in therinsing cycles of a washing machine. The basic composition e.g. in theform of a tablet is dissolved during the main washing cycle and canevolve its corresponding, intended action (cleaning, water softening,washing intensification, etc.). The particle according to the inventioncontains as the core material the substance or substances having toevolve their main function in the rinsing cycles of the washing machine.Said substance or substances are protected by a covering which, at theconcentration of the specific compound, e.g. the pH-value, and thetemperature of the main washing cycle, is stable and dissolves or isdetached either insignificantly or not at all.

Following the main washing cycle and the pumping out of the washingliquor a dilution effect occurs in the rinsing cycles through therepeated entry of fresh water, so that the concentration of the specificcompound drops significantly. Obviously the actual course of thisconcentration change in the washing cycle of a washing machine isgreatly dependent on the composition of the detergent used. Thefollowing table 1 shows in exemplified manner a pH-profile measured inthe case of a CANDY Activa 80

Plus washing machine, with a 60° washing program with 3 kg of fabricshaving a normal dirtiness level and 3 standard 40 g detergent tablets,as described in detail hereinafter (example 4 ).

TABLE 1 Time (min) pH-value Main washing cycle  10 10.35  20 10.30  3010.28  40 10.27  50 10.27  60 10.27  70 10.27  80 10.25  90 10.25 Firstrinsing cycle 103 9.93 Second rinsing cycle 109 9.50 Third rinsing cycle119 8.90 Fourth rinsing cycle 128 8.50

It is clear throughout the main washing cycle there is a relatively highpH-value of 10.25 to 10.35, which by the fourth rinsing cycle hasdropped to 8.50. The solubility of the covering material mustconsequently be reduced to such an extent at pH-values of preferablybelow 9 that it rapidly dissolves or is detached and that the effectivecore material is released into the surrounding medium, i.e. the rinsingwater.

It is essential that the protection of the core material is effectivefrom the addition to the composition according to the invention to thewater up to the start of the rinsing cycles, i.e. also before thewashing liquor reaches a sufficiently high concentration of the specificcompound, as will be explained hereinafter.

As an alternative to the preferably used tablet form of the basiccomposition other administration forms are possible and covered by theprotective scope of the present invention. Thus, the particles with thecovering variable in its solubility in response to a change in theconcentration of the specific composition can be connected by agranulation or similar process to the basic composition, can e.g. beenveloped. In order to ensure for the said embodiment an optionallydesired reduced contact between the covering and the basic composition,the particles can be surrounded with a further protective jacket, whiche.g. comprises a compound soluble in water independently of theconcentration of the specific compound. With this embodiment during themain washing cycle once again firstly the basic composition and theprotective jacket of the particles were dissolved and once again theparticles protected by the covering according to the invention were leftbehind.

Provided that there is to be no charging by special dosing aids able toretain the particles according to the invention, the particles accordingto the invention must be chosen sufficiently large that they are notdischarged to a significant extent during pumping out of the washingmachine following the main washing cycle and the first rinsing cycles orcharging by charging devices.

The invention is described in greater detail relative to the followingexamples and the drawings, wherein show:

FIG. 1 A first embodiment of the composition according to the inventionin cross-section.

FIG. 2 A second embodiment of the composition according to the invention in cross-section.

FIG. 3 A third embodiment of the composition according to the inventionin cross-section.

FIGS. 4a & b A fourth embodiment of the composition according to theinvention in cross-section and in plan view.

FIG. 5 A fifth embodiment of the composition according to the inventionin cross-section.

FIGS. 1 to 5 constitute possible embodiments of the compositionaccording to the invention. In all cases for illustration the preferredtablet form is chosen.

FIG. 1 shows a tablet 1 comprising two half-tablets 2, 3, which can havedifferent or identical compositions. Roughly centrally in bothhalf-tablets there is a roughly hemispherical recess 4, 5, which whenthe tablet 1 is combined together give a roughly spherical cavity.

In the represented embodiment said cavity receives a single particle 6comprising the core 8 and covering 9, whose external diameter isslightly smaller than the internal diameter of the tablet cavity. Inanother embodiment of the invention particles 6 can also completely fillthe cavity of the tablet and engage on the walls thereof. If theinternal diameter of the cavity is slightly larger than the externaldiameter of the particles 6, the latter can either be loosely receivedin the cavity or fixed by an adhesive applied in the gap.

In the embodiment in which the contact between the particle and thebasic composition surrounding it is reduced or completely prevented, theadditional advantage arises that during production processes, e.g. themoulding of the individual ingredients in successive stages, adeformation and possibly resulting damage to the core or cores and/orthe covering is reliably prevented and which could give rise to areduction in the protective action of the core covering. By preventingany pressure being exerted on the particle during any phase of theproduction process, it is possible to reliably ensure that with aspecific composition of the core or cores there is no “bleeding” thereofinto the material of the covering and basic composition. It can beadvantageous with certain compositions of the covering 9 and/or basiccomposition 2, 3, to avoid an intimate, full-surface contact, becauseotherwise undesired reactions could occur in the boundary layers.

In a preferred embodiment of the invention the surface of the particleis at the most in partial direct contact with the surface of the tabletbasic composition surrounding it. This can take place in the mannerspecifically described in the application, but also in other waysachieving the sought objective. Examples are the loose arrangement ofthe smaller particle in a larger cavity, the fixing of a smallerparticle in the larger cavity in such a way that there is no or only apartial contact between the particle and the basic composition, theapplication of a protective coating over the core covering according tothe invention, etc.

In conjunction with the inventive particle, the expression “localenvironment” means the direct environment around said particle. Theconcentration of the specific compound in said local environment of theparticle is the determinative factor for its stability. In preferredembodiments in tablet form said concentration in the local environmentof the particle is determined at least up to a substantially completedissolving of the tablet by said molecule passing into solution. Thus,at least in the initial phase of the main washing cycle, the origin ofthe “specific compound” is a compound from the basic composition formingthe tablet or is produced by the latter in the surrounding medium. Inthe most typical case the basic, standard detergents are OH⁻ ions, whoseconcentration can be expressed as a pH-value.

If the basic composition is not constituted by an e.g. basic detergentcomposition, but instead e.g. by a water softener composition or awashing intensifier composition, the protection of the covering of theparticle by a sufficiently high concentration of the specific compoundin the local environment of the particle is possibly only ensured untilthe basic composition, e.g. the tablet is completely dissolved, namelyin cases where the basic composition is unable to make available asufficiently high, corresponding concentration in the washing liquor. Insuch cases the sufficiently high concentration in the washing liquor(and therefore in the local environment of the particle or particles) isbrought about by dissolving the detergent (or a further specificadditive).

For fixing the particle in the cavity it is obviously not only possibleto use a conventional adhesive, but also other compositions and agentsfulfilling the same function, e.g. a mechanical fixing such as e.g.adequate frictional engagement between tablet and particle at at leastcertain points or a plug connection between tablet and particle. Fixingagents between the particle and tablet can also be constituted bycompounds which preferably melt or dissolve during the main washingprocess.

Obviously, the most varied further geometrical shapes, such as e.g.ellipsoid, cylinder, etc. are possible for the design of the cavity inthe tablet or the particle received therein. The design and size of thetablet cavity and that of the particle received therein need notcorrespond with one another. Thus, e.g. a spherical cavity can receive acylindrical particle. All possible further combination possibilities areconceivable within the scope of the present invention. It is alsopossible to fill the cavity with several smaller particles instead of asingle particle.

FIG. 2 shows a second embodiment of the inventive composition based on aconventional two-layer tablet 1. In this case the upper half-tablet 3comprises two parts, which make available both an adequate cavity 5 forreceiving the particle 6 and an opening to the tablet side 11. Thus, inthis case the particle 6 is not completely surrounded by the basiccomposition of the tablet 1, so that it is visible from the outside inthe interior of tablet 1. Here again the particle can either be looselyreceived in the cavity 5 (provided that it is ensured by a correspondingchoice of the size of the particle 6 on the one hand and the size of theopening of the cavity 5 towards tablet side 11 on the other that theparticle or particles in the cavity cannot pass through the opening) orcan be fixed in the interior of the cavity 5 by a corresponding agent,such as e.g. an adhesive.

FIG. 3 shows a third possible embodiment, once again based on atwo-layer tablet. By means of a suitable device a depression 4 is formedin the upper layer 2. Into said depression 4 is introduced the particle6, which in this case, because the depression is open to such an extentto the side 11 of the tablet 1 that without fixing the particle mightdrop out of the depression, is fixed with an adhesive 10 or a fixingintermediate layer or mechanically (e.g. by frictional engagement) inthe depression. This principle can obviously also be applied tosingle-layer tablets.

Here again the most varied geometrical configurations are possible.Thus, e.g. parallel to side 11, the depression can have a substantiallycircular cross-section. However, numerous other cross-sections areconceivable, e.g. any random polygon. The particle 6 received in thedepression 4 can, as in the embodiment according to FIG. 2, assume anyrandom shape (independent of the shape of the depression 4), such ase.g. an ellipsoid, cylinder, parallelepiped, etc.

Consideration can also be given to fixing the particle 6′ in a tabletcavity open on both sides, in the tablet, such as in a cylindrical hole4′ passing through a tablet body 1′ comprising a layer 2′ and in whichis fixed a corresponding cylindrical particle 6′ having a core 8′ and acovering 9′ (FIGS. 4a and b).

Another possible embodiment can be gathered from FIG. 5. The latter issubstantially built up in the same way as the embodiment according toFIG. 3. However, in the present case the particle 6″ contains not onecore (as in FIG. 3), but a plurality of cores 8″, which are all embeddedin a covering 9″. In this embodiment it is e.g. also possible toincorporate into a particle 6″ cores having a different composition anddifferent shape (encapsulated material or solid cores).

Both in the represented embodiments and also in further conceivablealternatives it is important that for the particle containing thesubstance or substances to be released during the rinsing cycles, atleast in the first phase of the main washing cycle, there is a localenvironment with an adequate ionic concentration or pH-value which canserve as a “trigger” for dissolving the covering, i.e. in a phase inwhich the detergent composition has not yet adequately dissolved, i.e.the pH-value is still relatively low, i.e. temporarily in an area withan increased solubility of the covering. This ensures that the coveringhas an adequate stability up to the rinsing cycles.

EXAMPLE 1 Production of the Core

a. Core for a Particle for the Controlled Release of Acid in the RinsingCycle

The release of an acid in the rinsing cycles of a washing machine servesboth to remove incrustations and for neutralizing alkaline residues.Advantageously use is made for this purpose of weak acids, such asamidosulphuric acid and/or maleic acid. These materials areconventionally solids, which can be directly provided with the intendedcovering and the coating process must optionally be matched to thecorresponding substance or substances.

In the production process a mixture of 1.05 g of amidosulphuric acid and0.45 g of maleic acid are shaped to a tablet in a rotary press under apressure of 890 kg/cm².

b. Core for a Particle for the Controlled Release of a Fragrance in theRinsing Cycle

Whilst taking account of similar considerations to those of example 1a,a corresponding core is produced in the following manner. 0.1975 g offragrance-are absorbed on 0.0525 g of finely divided silica, in order togive a free-flowing, granular material. The resulting 0.25 g are mixedwith 0.6 g of microcrystalline cellulose and 0.15 g of cross-linkedpolyvinyl pyrrolidone. The mixture is tabletted in a circular press withan internal diameter of 10 mm under a pressure of 2900 kg/cm² in orderto provide an elliptical tablet with a height of 13.1 mm and a weight ofapproximately 1 g.

Alternatively fragrances, normally in the form of liquids, can beprovided as fragrance-containing capsules.

c. Core for a Particle for the Controlled Release of Chlorine Bleach inthe Rinsing Cycle

Chlorine bleach is used in the rinsing cycle of a washing machine forimproving the cleaning action and also simultaneously has a disinfectingaction.

Taking account of the considerations of examples 1a and 1b, such corescan be produced in the following way. 1 g of chlorine bleach, e.g. puresodium dichloroisocyanurate, can be pressed to a tablet in a suitablepress under a pressure of 5600 kg/cm².

d. Core for a Particle for the Controlled Release of a FabricConditioning Activity in the Rinsing Cycle

In the present example the core comprises several substances, which areto evolve their given actions in the rinsing cycle of a washing machine.In the present case it is specifically a combination of a fabricsoftener, an agent for reducing the build-up of static electricity inthe fabric and an agent for improving the renewed fabric moistureabsorption.

A suspension of 58% urea, 18% dimethyl distearyl ammonium chloride(DMDSAC) (90%), 8% of a C₉₋₁₁ alcohol, ethoxylated with 9 mole ofethylene oxide and 16% of water was prepared. The suspension wasspray-dried in order to give a granular material with a density of 580g/l and the following composition: 68.8 wt. % urea, 19.2 wt. % DMDSAC,9.5 wt. % nonionic surfactant and 2.5 wt. % water.

4 g of the granular composition were mixed with 1 g of cellulose. Themixture was tabletted in a circular press with an internal diameter of25 mm and a pressure of 80 kg/cm² in order to give an elliptical tabletwith a height of 14 mm and a weight of 5 g.

EXAMPLE 2 Screening Process for Covering Materials

As stated hereinbefore, it is of vital significance for the presentinvention that the material for covering the particle core or corescomprising the substance evolving its function essentially during therinsing cycle, has a solubility which is dependent on the concentrationof a specific, selected ion. In this way the covering is substantiallyinsoluble in the main washing cycle and is made soluble and detachesfrom the particle if the concentration drops during the rinsing cycles.

It has been observed that the dilution resulting from the pumping out ofwashing liquor and the inflow of fresh water during the differentrinsing cycles leads to the concentration dropping by 20 to 200 timesbetween the end of the main washing cycle and the last rinsing cycle.

On the basis of this observation a process for screening the suitabilityof different polymers for their use as covering materials was developed,which is based on the determination of the solubility of such polymersat two different concentrations, which are at least 20 times andpreferably 200 times apart.

The values for the concentration to be used during polymer screening,are dependent on the formulation of the basic composition of the tabletin which the enveloped particle is to be incorporated.

In fact, the value for the highest concentration to be used for thescreening process should correspond to the concentration of the selectedion encountered in the washing liquor, after the detergent hascompletely dissolved. When this concentration has been determined, thelower value for the concentration should be fixed at 20 to 200 timesbelow said higher value.

On the basis of this information at falls within the routine capacityand knowledge of an expert in this field to determine the values for theconcentration of the test solutions to be used in the testing processesdescribed hereinafter.

Process for the Preparation of the Test Solution and for Performing andEvaluating the Test

The materials to be tested are dissolved in solvents, in which they arereadily soluble. The solutions are spread over glass plates andsubsequently dried at room temperature until they have a constantweight.

At a controlled temperature the glass plates are paced in a beaker withthe test solution. The solution is ten stirred with a magnetic stirrerat a controlled stirring rate. After about 10 minutes the glass platesare removed from the beaker and dried at room temperature to a constantweight. The results are expressed as a weight loss (%)

Obviously the screening processes must be adapted to the composition ofthe detergent, because this exerts the essential influence on theconcentration or pH-profile in the washing cycle. The aim in all casesis to check the degree of solubility of the corresponding materials atdifferent states, namely high or low concentration or pH-value.

On the basis of this information it falls within the routine capacity ofan expert in this field to provide the specific test parameters for thescreening. For example, hereinafter two screening processes aredescribed with some of the possible materials for the covering of theparticles.

Screening Process 1

Screening process 1 was carried out with buffer solutions as the mediumfor simulating the washing liquor. To this end two buffer solutions wereprepared in the following way:

Stock solution: 7.507 g glycine buffer (Merck 104169) 5.850 g NaCltopped up with water to 1000 ml pH 8-buffer solution: 500 ml stocksolution 500 ml distilled H₂O 1.23 g 1N NaOH pH 10-buffer solution: 500ml stock solution 500 ml distilled H₂O 32.6 g 1N NaOH.

Screening Process 2

Screening process 2 was performed with the following detergentformulation in order to simulate the conditions in different stages of awashing cycle.

Detergent Formulation

Firstly a spray-dried basic material with the following composition wasprepared:

TABLE 2 Ingredient wt. % Sodium carbonate 7.43 Sodium LAS 40.0 Zeolite17.70 Polymer 7.0 Sodium sulphate 9.61 Sodium-silicate 7.00 Soap 4.0Phosphonate 1.55 Carboxymethyl cellulose 1.01 Water and others 4.7

This spray-dried basic composition was mixed with the further, followingingredients in order to obtain the final formulation:

TABLE 3 Ingredient wt. % Spray-dried basic material 22.6 Sodiumpercarbonate 20.0 Sodium carbonate 19.58 Sodium tripolyphosphate 17.42Microcrystalline cellulose 6.0 Alkyl sulphate 6.0 Polymer 1.50Cross-linked polyvinyl pyrrolidone 1.80 Enzymes 1.78 TAED 1.00Polyethylene glycol 0.18 Water and others 2.14

Screening Process 3

Screening process 3 is used for screening for compounds, whosesolubility changes as a function of the concentration of potassium ions.The compounds revealed by such screening processes can be used if in themain washing cycle, as described hereinbefore, there is acorrespondingly high potassium ion concentration, which iscorrespondingly reduced by dilution in the rinsing cycles.

Screening process 3 was carried out with the following formulation inorder to simulate corresponding conditions.

Formation

Ingredient wt. % Potassium tripolyphosphate 13.6 Potassium bicarbonate34.0 Potassium sulphate 23.1 Potassium chloride 12.4 Potassium carbonate9.7 Boric acid 2.0 Sodium perborate monohydrate 2.0 TAED 1.0 Paraffin1.0 Protease 0.2

EXAMPLE 3 Selection of Materials for Covering the Particles

Using the screening process described in example 2 various materialswere tested for their suitability as a covering for the particlesaccording to the present invention. One of these materials, hereinafter“polymer 1” is a polymer of the type described in Japanese patentapplication KOKAI 61-28440, i.e. a polymer of general formula II withl/(l+m+n)=0.35; m/(l+m+n)=0.45; l+m+n=1500-1800.

The polymer was produced in the conventional manner by bulkpolymerization. The screening test results were as follows:

Screening Process 1:

Films of polymer 1 were produced from a 10% solution in isopropanol.

pH-value of buffer Weight loss of 30° C. Weight loss at 60° C. solution(%) (%) 10 7-8 5-8  8 81-88 91-95

Screening process 2 gave similar results.

The invention is obviously not restricted to this exemplified polymerand naturally a considerable variation possibility exists with respectto the polymers mentioned in Japanese patent applications KOKAI60-141705, 61-28440, 61-28441, 61-28596, 61-28597 and 61-28598 or can beextended to compounds of formula IV:

in which R₁ independently of one another is hydrogen or an alkyl groupwith 1 to 3 carbon atoms, R₂ independently of one another is hydrogen oran alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.

In addition, within the larger class of compounds according to formulaIII:

in which G is a link group selected from —COO—, —OCO—, —CONH—, —NHCO—,—NHCONH—, —NHCOO—, —OCONH— or —OCOO—, R₁ independently of one another ishydrogen or an alkyl group with 1 to 5 carbon atoms and x is an integerfrom 1 to 6, in exemplified manner it is possible to use polymers with arepeat unit based on a compound of formula V:

e.g. a pH-sensitive polymer (“Polymer 2”) with the repeat unit VI, whichis commercially available from SANKYO under the trade name AEA®:

The above-described screening process 2 was also performed with “Polymer2”:

15 g of “Polymer 2” and 5 g of Mowiol® 3-98 (Clariant) were dissolved in200 ml of a mixture of water/ethanol/1 N HCl 12:8:1. Films were formedand tested, in the manner described hereinbefore. The results werecomparable with those for “Polymer 1”.

Further polymers having the desired characteristics or which can bemodified in a simple manner so that they are suitable for the purposesof the present invention are polymers of isomers or derivatives ofpyridine, preferably copolymers with styrene or acrylonitrile, accordingto the following formulas VII and VIII, in which G is a substituent at arandom point of the pyrridine ring:

A polymer according to the above formula VIII, namelypoly(4-vinylpyridine-styrene) copolymer (Scientific Polymer ProductsInc.), namely “Polymer 3” was tested in accordance with theabove-described screening process 2:

10 g of “Polymer 3” were dissolved in 230 ml of water/1N HCl 6.25:1. Thefilms were formed and the tests carried out in the manner describedherein-before. The results were comparable with those for “Polymer 1”and “Polymer 2”.

Further polymers are (e.g. random) polymers derived from chitosan, basedon the following monomer units IX and X:

In addition, it is also possible to use in the core material coveringsubstances or substance mixtures which, with respect to their solubilitybehaviour, react to a change in the ionic concentration, i.e. ionicconcentration-sensitive polymers. Consideration for this purpose cane.g. be given to the partly hydrolyzed polyvinyl acetates (commerciallyavailable under the trade mark Mowiol®—Clariant) described in EP 284 191A2 and EP 284 334 A2 and which reveal a corresponding ionicconcentration dependence in the presence of borates due to thecomplexing of the borates with polyols. The first successful tests wereperformed with Mowiol® 56-88.

A further ionic concentration-sensitive polymer is the polysaccharideK-carrageenan, which was proved to be in screening process 3 (cf.example 2) a polymer whose solubility is dependent on the potassium ionconcentration in the surrounding medium. K-carrageenan is represented bythe following formula XI:

This polymer, known as “polymer 4”, was tested in accordance with theabove-described screening process 3:

4 g of K-carrageenan were dissolved in 96 g of water. 10 g of Mowiol®18-88 were dissolved in 90 g of water and both solutions were mixedtogether. The resulting solution was used for the formation of films andthe performance of tests in the manner described hereinbefore. Thefollowing results were obtained:

Concentration cleaning Weight loss at 30° C. Weight loss at 60° C. agent(%) (%)   4 g/l 0.5-0.3 11.0-12.0 0.02 g/l 24.5-25.0 78.0-85.0

The above list of compounds which are suitable for the inventivecovering is obviously non-exhaustive. Further polymers, which changetheir solubility by modifying the concentration of a specific compound,e.g. the pH-value in the desired range are conceivable or can bedeveloped and are consequently also covered by the protective scope ofthe invention. Inter alia, for the covering according to the inventionit is also possible to consider compounds which, with respect to theirsolubility behaviour react to the change in the concentration onnonionic compounds in the surrounding medium. The substances suited forthe inventive covering are not limited to polymeric compounds, althoughthey are described here as preferred embodiments.

With the aid of the aforementioned screening processes or screeningprocesses adapted to the measurement of an ionic concentrationsensitivity, it is possible to test for their suitability in the presentinvention various other commercially available materials or materialsobtainable by simple modifications. In view of the clear aims set andthe indicated screening processes, the choice of such polymers is aproblem which can be solved without difficulty by the average expert.

EXAMPLE 4 Production of a Particle According to the Invention

The different cores described in example 1 were uses as a basis forproducing the particle according to the invention. These cores wereindividually or in plurality (FIG. 5) provided with a covering in anapparatus for the application of a film coating, such as is known fromthe pharmaceutical industry (e.g. from Lodige, Huttlin, GS, Manesty antDriam).

In the case where the core or cores have an ingredient revealing acertain incompatibility with the material of the covering, prior to theapplication of said covering the core or cores can be initially providedwith a protective coating. For this purpose use can be made of variousprior art materials such as e.g. cellulose, cellulose derivatives,polyvinyl alcohol, polyvinyl alcohol derivatives and mixtures thereof.When using the cores of example 1, in cases 1 a, 1 b and 1 c such aprotective coating was used, namely a 10 wt.% aqueous solution of thepolyvinyl alcohol Mowiol® 5-68 (Clariant). In the case of example 1 athe core was coated with 0.76 g of such a solution, whereas in example 1b 0.40 g of the same solution was used and in example 1 c 0.29 g of thesame solution was used.

The covering can fundamentally be applied in any random quantity andthickness to the core or cores or the protective coating, provided thatit is ensured that the covering sufficiently rapidly dissolves or isdetached during the rinsing cycles to enable the substance or substancescontained in the core or cores to evolve their action. In a preferredembodiment to the cores are applied 1 to 10, preferably 4 to 8 wt. % ofthe ionic concentration-sensitive covering material (solids), based onthe weight of the complete

Preferably the particles according to the invention should have a sizesuch that they are not or at least not to a significant extentdischarged from the washing machine through the pumping out processesfollowing the main washing cycle or the individual rinsing cycles. Forthis purpose normally a maximum diameter of approximately 1 cm isadequate. Smaller or larger dimensions can obviously also be chosen,provided that operation is ensured.

For the further tests “polymer 1” from example 3 was used as thecovering and applied as a 10% polymer solution 0.055 N aqueous HCl.

Example 5 Production of a Tablet with the Particle According to theInvention

In exemplified manner hereinafter the production of a one or two-layertablet, in which both layers have the same composition, is described.Such a tablet can be produced by moulding the pulverulent ingredients inmachines known from the prior art and using the operating parametersknown from the prior art. The composition of such a tablet is based oncommercially available products. For example, hereinafter a detergenttablet, a water softener tablet and a washing intensifier tablet aredescribed.

Detergent Tablet

The composition mixture for a detergent tablet can e.g. be based on adetergent formulation as represented in example 2, tables 2 and 3. Theresulting granular composition has a bulk density of approximately 690g/l and can be tabletted under a pressure of 21 kg/cm² in order to givea half-tablet with a depression and weighing approximately 20 g.

An inventive particle produced according to example 1 and 4 isintroduced into the half-tablet recess. Subsequently a fixing substancee.g. an adhesive (e.g. polyethylene glyccl, polyvinyl ether, polyvinylalcohol, silicate, preferably melted PEG 4000) is applied to thecorresponding face of the half-tablet and optionally also to theparticle and the second half-tablet is pressed onto the firsthalf-tablet with the particle according to the invention. This gives adetergent tablet with a commercially convectional weight of about 40 g.

Water Softener Tablet

The following ingredients were mixed:

TABLE 4 Ingredient wt. % Sodium carbonate 20 Trisodium citrate 20Polymer 18.5 Schist silicate 10 Microcrystalline cellulose 10Polyethylene glycol 6000 10 Phosphonate 3 Water 8.5

The resulting granular composition was tabletted under a pressure of 150kg/cm² in order to give a half-tablet with a recess and weighingapproximately 8 g.

The placing round the particle according to the invention and thejoining together of the half-tablets took place in the manner describedfor the detergent tablet.

Washing Intensifier Tablet

Using known technology for producing a two-layer tablet a washingintensifier tablet is produced, whose differently heavy layers (26/74)have a different composition in accordance with the following table:

TABLE 5 First layer (26%) Second layer (74%) Ingredient wt. % wt. %Sodium percarbonate 75.93 Citric acid 17.50 5.13 Microcrystallinecellulose 7.00 7.00 Schist silicate 5.00 5.00 Enzymes 5.06 Sodiumbicarbonate 9.94 1.37 TAED 50.00 Polyethylene glycol 6000 4.00 4.00Polyvinyl pyrrolidone 1.50 1.50 Miscellaneous 0.068

As shown in FIG. 3 a depression is formed in the upper layer in whichinitially an adhesive or the like is introduced, followed by theparticle according to the invention.

The features of the invention disclosed in the description, claims anddrawings can be essential to the implementation of the differentembodiments of the invention, either singly or in random combination.

What is claimed is:
 1. A composition for use in a laundry machine,comprising a tablet composition having a basic composition, the tabletcomposition performing its function in a main washing cycle of thelaundry machine, a particle having a core and comprising a componentperforming its function in a rinsing cycle of the laundry machine, and acovering surrounding the core and comprising a compound whose solubilityis inversely proportional to a concentration of a basic ion in a mediumsurrounding the particle, wherein the particle is arranged in or on thetablet such that only a portion of a surface of the particle directlycontacts the tablet, and wherein the concentration of the basic ioncaused by dissolution of the tablet composition in the main washingcycle is sufficiently high to prevent dissolution of the particlecovering or detachment of the covering from the particle core up to astart of the rinsing cycle.
 2. The composition according to claim 1,wherein the particle is coated with a substance which, independently ofthe concentration of basic ion in the surrounding medium, dissolves orseparates during the rinsing cycle.
 3. The composition according toclaim 1, wherein the particle is received in a cavity of the tablet, andwherein the cavity encloses the particle.
 4. The composition accordingto claim 3, wherein the cavity has a volume equal to a volume of theparticle received therein.
 5. The composition according to claim 3,wherein the cavity has a larger volume than a volume of the particlereceived therein.
 6. The composition according to claim 5, wherein theparticle is loosely arranged in an interior of the cavity.
 7. Thecomposition according to claim 5, wherein the particle is fixed in aninterior of the cavity.
 8. The composition according to claim 7, whereinthe particle is fixed by an adhesive.
 9. The composition according toclaim 3, wherein the cavity is centrally arranged in an interior of thetablet.
 10. The composition according to claim 3, wherein the cavity isspherical.
 11. The composition according to claim 5, wherein the cavityis spherical and the particle is spherical.
 12. The compositionaccording to claim 1, wherein the particle is received in a cavity ofthe tablet, and wherein the cavity only partly surrounds the particle.13. The composition according to claim 3, wherein the cavity is adepression in a surface of the tablet.
 14. The composition according toclaim 13, wherein the particle is so received in the cavity that it doesnot project beyond a surface of the tablet.
 15. The compositionaccording to claim 14, wherein the cavity contains only a singleparticle, and a volume of the particle is equal to a volume of thecavity.
 16. The composition according to claim 15, wherein the cavityhas a substantially circular mouth.
 17. The composition according toclaim 16, wherein the mouth of the cavity is smaller than a diameter theparticle received therein.
 18. The composition according to claim 17,wherein the particle is loosely arranged in the cavity.
 19. Thecomposition according to claims 17, wherein the particle is fixed in thecavity.
 20. The composition according to claim 19, wherein the particleis fixed with an adhesive.
 21. The composition according to claim 1,wherein the tablet composition is selected from the group consisting ofa detergent composition, a water softener composition, a washingintensifier composition, and combinations thereof.
 22. The compositionaccording to claim 1, wherein the covering comprises a compound which issoluble in a medium of the rinsing cycle such that it becomes dissolvedor detached from the particle core to allow release of a material of thecore into the medium of the rinsing cycle.
 23. The composition accordingto claim 22, wherein a solubility of the compound is inverselyproportional to hydroxide ion concentration in the surrounding medium.24. The composition according to claim 23, wherein at a pH-value above10 the compound has no or only a limited solubility and at a pH-valuebelow 9 the solubility is such that the compound becomes dissolved ordetached from the particle core.
 25. The composition according to claim22, wherein the compound comprises a polymer.
 26. The compositionaccording to claim 25, wherein the compound comprises a pH-sensitivepolymer incorporating a repeat unit, which has a basic function separatefrom a backbone chain of the polymer.
 27. The composition according toclaim 26, wherein the repeat unit is based on a compound selected fromthe group consisting of vinyl alcohol derivatives, acrylates and alkylacrylates having the basic function.
 28. The composition according toclaim 26, wherein the polymer is a carbohydrate functionalized with thebasic function.
 29. The composition according to claim 26, wherein thebasic function is an amine.
 30. The composition according to claim 29,wherein the amine is a secondary or tertiary amine.
 31. The compositionaccording to claim 29, wherein the repeat unit is based on a compound offormula III:

in which G is linking group selected from —COO—, —OCO—, —CONH—, —NHCO—,—NHCONH—, —NHCOO—, —OCONH—or—OCOO—, each R₁ is, independently, hydrogenor an alkyl group with 1 to 3 carbon atoms, each R₂ is, independently,hydrogen or an alkyl group with 1 to 5 carbon atoms, and x is an integerfrom 1 to
 6. 32. The composition according to claim 29, wherein therepeat unit is based on a compound of formula IV:

in which R₁ is hydrogen or an alkyl group with 1 to 3 carbon atoms, eachR₂ is, independently, hydrogen or alkyl group with 1 to 5 carbon atoms,and x is an integer from 1 to
 6. 33. The composition according to claim26, wherein the basic function is a basic aromatic N-containing group.34. The composition according to claim 33, wherein the basic function isa pyridine group.
 35. The composition according to claim 33, wherein thebasic function is an imidazole group.
 36. The composition according toclaim 28, wherein the polymer is derived from chitosan.
 37. Thecomposition according to claim 23, wherein the composition comprisesk-carrageenan.
 38. The composition according to claim 1, wherein thecore comprises a material selected from the group consisting offragrances, fabric softeners, antistatic agents, agents for restoring acapacity of washed articles to absorb moisture, mild acids, bleaches,disinfectants, agents for permanent protection both of a washed articleand a person wearing the washed article against insects or mites, agentsfor improved removal of grease stains, finishing agents givingprotection against creasing, optical brighteners, ironing auxiliaries,agents for inhibiting dye transfer, enzymes, and combinations thereof.39. The composition according to claim 38, wherein a portion of the corecomprises an encapsulated liquid.
 40. The composition according to claim38, wherein the core is in solid form.
 41. A process for washingarticles in a laundry machine, comprising introducing into the laundrymachine during a prewashing cycle or a main washing cycle a tabletcomposition comprising a basic composition, the tablet compositionperforming its function in a main washing cycle of the laundry machine,a particle having a core and comprising a component performing itsfunction in a rinsing cycle of the laundry machine, and a coveringsurrounding the core and comprising a compound whose solubility isinversely proportional to a concentration of a basic ion in a mediumsurrounding the particle, wherein the particle is arranged in or on thetablet such that only a portion of a surface of the particle directlycontacts the tablet, and wherein the concentration of the basic ioncaused by dissolution of the tablet composition in the pre-washing ormain washing cycle is sufficiently high to prevent dissolution of theparticle covering or detachment of the covering from the particle coreup to the start of the rinsing cycle.
 42. The process according to claim41, further comprising a step of introducing an additional detergentinto the laundry machine during the main washing cycle.